The successful development of parasitic nematodes is intimately associated with their ability to molt. Few studies have provided detailed information on cutticle formation in parasitic nematodes. The general objectives of the present research are (1) to correlate biochemical and morpholical events in relation to RNA and protein synthesis during a molting phase in Nippostrongylus brasiliensis; and (2) to determine the time sequence of the events in cutticle formation. Standard isotope and inhibition techniques will be employed to elucidate patterns of RNA and protein synthesis. Light and electron microscopic techniques will be used for evaluating morphological aspects of cuticle formation.